Jason Burke and Dan de Luce in Tehran Sunday October 5, 2003 The Observer

Secret 'back-door' diplomacy involving some of the Middle East's most influential figures has led to unexpected signals of a rapprochement between America and Iran despite angry public rhetoric on both sides. Tensions between Washington and Tehran remain high, particularly over the question of Iran's nuclear programme and alleged attempts to destabilise the US occupation in Iraq, but a tentative dialogue has been established.

One go-between has been King Abdullah II of Jordan, who visited Tehran shortly before meeting President Bush at Camp David last month. King Abdullah is understood to have been briefed by Mohammed Khatami, the Iranian president, and Kamal Kharrazi, the foreign minister, and to have transferred their 'analysis of the regional situation' to the Americans.

Last week US officials confirmed that they had received 'positive signals' from Iran. 'There is some indication that the Iranians want to talk to us about a range of issues and we are responding appropriately,' one State Department official said.

However, analysts say that different groups in Iran are reacting to the country's new security situation in different ways, and the seemingly contradictory stances reflect deep divisions within Iranian politics and society. Religious hardliners, who control many of the key institutions, are taking a firm stance over Iran's nuclear programme and are working to cause problems for the US-led forces in Iraq. However, Iranian reformists, such as Khatami and Kharrazi, are taking a more conciliatory position.

Iran is expected to attend an international donors conference on the post-war reconstruction of Iraq in Madrid later this month, while continuing to take a hard line on the nuclear issue.

'As much trouble as we have with them on the nuclear issue, we have a slightly different relationship with them on Iraq,' Richard Armitage, the American deputy secretary of state, said last week. 'They have big interests in stability in Iraq.'

Another issue causing tensions is the alleged presence of senior al-Qaeda figures in Iran. Here differences in the US administration mirror those in Iran. American hawks, particularly those close to Defense Secretary Donald Rumsfeld, claim that Iranian hardliners are harbouring militants and facilitating their terror campaign. Their opponents in Washington say that any Sunni Muslim Islamic militants held by the Iranian regime are in prison and unable to operate.

The most pressing issue for all remains the suspicion that Iran is trying to develop a nuclear bomb.

The International Atomic Energy Agency (IAEA) has asked for prompt access to sensitive nuclear sites, giving Iran one last chance to come clean about the true nature of its nuclear programme.

Inspections last summer found traces of weapons-grade uranium and obstruction of the IAEA's work could lead to UN sanctions. The IAEA has demanded that Iran cease all uranium enrichment activity and prove it has no weapons programme by 31 October.

Senior Iranian conservatives last week dismissed the terms of the 31 October deadline. At the weekly Friday prayers ceremony at Tehran University, the powerful former president, Akbar Hashemi Rafsanjani, condemned the IAEA resolution.

'The hypocritical policy of the Americans and Westerners has no justification,' Rafsanjani told worshippers amid chants of 'Death to America', though he did indicate that Iran would be willing to meet some international demands in return for guarantees protecting Iran's sovereignty.

Dr Ali Ansari, lecturer in Middle Eastern history at the University of Durham, said that the nuclear issue united many reformists and conservatives. 'Many believe it is their national right to develop a nuclear programme,' he said.